1. Field of the Invention
The present invention relates to a method for optimizing a space vector pulse width modulation, in which a voltage is connected to a load by combining discrete switching states of a plurality of switches to control the load, the load being switched to zero potential by two of the switching states, and relates to a device for carrying out the method.
2. Description of the Related Art
“Space vector pulse width modulation” SVPWM is often used to operate polyphase machines, which, on the one hand makes possible a relatively good degree of control, and on the other hand is relatively simple to implement. In particular, the control signals for the three half-bridges that are required for operating a polyphase machine are generated in this context. The signals between the three half-bridges are phase-shifted by 120°. The three half-bridges include six switches having 8 admissible discrete switching states, which emit periodic signals. Six of the switching states are active, i.e. they lead to a voltage. Two switching states are designated as null vectors and do not conduct any voltage to the load.
The maximum degree of control of the inverter, which is controlled by the SVPMW method, is limited by a nonideal hardware. In order for the curve of the switched voltage to be able to follow the control signal, in the case of real power switches, a minimum distance in time tMin is required between two switching processes of the same switch, whereby the maximum degree of modulation AMax is reduced toAMax=(TPWM−2*tMin)/TPWM.  (1)
A null pointer that is to be present for a very short time, that is less than tMin, can no longer be set.